Railway braking apparatus



Aug. 17, 1943. H. BONE RAILWAY BRAKING APPARATUS Filed Feb. 11, 1942 2 Sheets-Sheet 1 HIS ATTORNEY Aug. 17, 1943. Y H. L BONE 2,326,924

RAILWAY BRAKING APPARATUS Filed Feb. 11, '1942 Z'Sheeu's-Sheet 2 Patented Aug. 17, 1943 v LIII RAILWAY BRAKING APPARATUS Herbert L. Bone, Forest Hills, Pa., assignor to The Union Switch & Signal Company, Swissvale, Pa., a corporation of Pennsylvania Application February 11, 1942, Serial No. 430,402

12 Claims.

My invention relates to railway braking apparatus, and particularly to braking apparatus of the type comprising wheel engaging braking bars located beside a track rail, and movable toward and away from the rail into braking and non-braking positions. More particularly, my invention relates to apparatus of the type described wherein the braking bars are arranged to be moved to their braking positions by means of one or more fluid pressure operated motors. and to be restored to their non-braking positions by suitable biasing means, such as gravity.

Specifically, my present invention relates to car retarder-s of the type described and claimed in my prior Patent No. 2,089,823, granted on August 10, 1937, for Railway braking apparatus, wherein the fluid pressure motors which operate the braking bars each have associated therewith a link which, together with the motor, forms a toggle that is normally collapsed when the motor is vented to atmosphere to provide a wide opening for the braking bars, but which moves to its dead center position in response to an initial movement of the motor piston when fluid is admitted to the motor to move the braking bars to their braking positions and thereafter remains in its dead center position during the remainder of the piston stroke.

It has been found desirable in braking apparatus of the type described to throttle the fluid supplied to the fluid pressure motors during the initial movement of the motor piston necessary to operate the toggle to reduce the speed of operation of the toggle cylinders while the retarder is closing in order to prevent excessive shock. This result can be accomplished by simply reducing the size of the inlet valve, or by providing an orifice in the inlet supply pipe, but these methods for accomplishing this result are open to the objection that they increase the time required for the fluid pressure to build up to full line pressure after the braking bars have reached their closed or braking positions.

One object of my present invention is to provide an inlet valve arrangement which will cause the inlet valve to throttle the supply of fluid pressure to the fluid pressure motors until the braking bars reach their braking positions and then cause the inlet valve to open fully to allow the pressure to build up rapidly to its full value.

According to my invention, the inlet valve is of the type operated by a shifting piston and has associated therewith two springs one of which biases the valve to its closed position, and the other one of which is arranged to be engaged by the valve when it has opened to the extent necessary to provide the desired initial throttle action referred to above. These springs are so proportioned that the valve will open its initial amount on a relatively low fluid pressure, but that, a relatively high fluid pressure is required to compress the second spring and produce full valve opening. The time required for the pressure to build up behind the shifting piston from the low to the high pressure is regulated by providing a choke in the inlet pipe through which fluid is supplied to the inlet valve to cause it to open, and also by providing a reservoir which communicates with the operating cylinder of the inlet valve. The supply of fluid pressure to the inlet pipe is controlled by a magnet valve, and a second reservoir is provided between the choke and the magnet valve for the purpose of decreasing the time required for the pressure to build up in the inlet valve chamber to that required to produce the initial opening of the valve.

Other objects and characteristic features of my invention will become apparent as the description proceeds.

I shall describe one form of braking apparatus embodying my invention, and shall then point out the novel features thereof in claims.

In the accompanying drawings, Fig. 1 is a view partly cross sectioned and partly diagrammatic showing one form of braking apparatus embodying my invention. Fig. 2 is a detail view showing the fluid pressure motor and associated toggle link illustrated in Fig. 1 in the positions which they occupy when the braking bars are moved to their braking positions.

Similar reference characters refer to similar parts in both views.

Referring to the drawings, the reference character I designates one track rail of a stretch of railway track, which track rail, as here shown, is secured to a rail support 2 mounted on an adjacent pair of the usual crossties 3, only one crosstie being visible in the drawings. Associated with the rail I is a car retarder comprising two brak ing bars Al and A2 located on opposite sides of the rail. Each of these braking bars comprises, as usual, a brake beam 4 and a brake shoe 5.

The braking bars Al and A2 are arranged to be moved toward and away from the rail I through the medium of a lever 6 which is pivotally mounted at one end on a pivot pin 8 carried by the rail support 2, and a lever 'l which is pivotally mounted intermediate its ends on the pivot pin 8. The lever B is inclined upwardly and extend away from the rail l and is provided in its upper surface with a groove 6a which receives the braking bar Al. The one end la of the lever is likewise inclined upwardly and extends away from the rail l at the opposite side of the rail from the lever 6, and the other end lb of the lever I is inclined downwardly and extends away from the rail 1 below the lever B. The end la of the lever l is provided in its upper surface with a groove 1c similar to the groove 6a in the lever B, which groove receives the braking bar A2. The parts are so arranged and so proportioned that if the outer or free ends of the levers 6 and 1 are moved apart, the braking bars will be moved toward the rails into their effective or braking positions. When the braking bars occupy their braking positions, the brake shoes will engage the opposite side faces of a car wheel traversing rail I, and will retard the speed of the car. The center of gravity of the lever B and braking bar Al is considerably to the right of the pivot pin 8 so that this lever will normally tend to rotate in a clockwise direction about the pivot pin. Similarly, the center of gravity of the lever 'l and braking bar A2 is to the left of the pin 8 so that this lever will normally tend to rotate in a counterclockwise direction about the pivot pin 8. It will be apparent therefore that when no force is applied to the free ends of the levers 6 and l to move them apart, the free ends of these levers will move toward each other, thereby moving the braking bars to their ineffective or non-braking positions in which they are illustrated in the drawings.

The levers 6 and 1 are arranged to be moved apart by means of a fluid pressure motor M comprising a cylinder l 2 partly closed at its lower end by a cylinder head 13, and pivotally connected at its upper end to the free end of the lever B by means of a pivot pin M. The cylinder head I3 is provided with a relatively large centrally located bushed bearing i5, and extending into the cylinder l2 through this bearing is a piston rod I6 that is driven by a piston 11, a part of which piston is formed integrally with the piston rod as will be apparent from an inspection of the drawings. The cylinder head is also provided with two laterally spaced depending brackets l8a which support rollers I9a, respectively (see Fig. 2). Only one bracket and one roller are shown in the drawings, but if a fuller showing and description is required reference may be had to my aforementioned Patent No. 2,089,823. A link comprising two parallel side members connected together by a Web is also pivotally connected intermediate its ends to the lower end of the piston rod i6 by means of a pivot pin 2|, and is pivotally connected at one end to the end lb of the lever 1 by a pin 22, thus operatively connecting the piston rod [6 with the lever 1. The side members of the link 20 at the end opposite that which is pivotally connected with the lever l are each provided, respectively, with integral laterally projecting cams 23a having cam surfaces 24a, and with laterally projecting cams 25a having cam surfaces 26a. The cam surfaces 24a and 26a cooperate with the rollers 19a. The side members of the link 20 are further provided with bosses 21a which cooperate with stop lugs 28a provided on the end lb of the lever I.

Fluid pressure may be admitted to the cylinder l2 through an opening 29 which is threaded to'receive a pipe 31. When fluid pressure is admitted to the cylinder, the piston i1 is forced downwardly within the cylinder from its retracted position in which it is shown in Fig. 1 to its projected position in which it is shown in Fig. 2. As the piston moves downwardly, the cam surfaces 24a engage the rollers Ilia, and these cams are so shaped that this engagement will cause the cylinder i2 to rotate in a clockwise direction about the pivot pin l4, and the link 20 to rotate in a counterclockwise direction about the pivot pin 22, until the link has been rotated to the position in which the bosses 21a on the link 20 engage the stop lugs 28a on the lever 'l as shown in Fig. 2. The parts are so proportioned that the link 20 will be rotated to the position in which the bosses 21a engage the stop lugs when the piston has moved downwardly from one-half to two-thirds of its total stroke, and that when the link 20 occupies this latter position, the toggle formed by the cylinder and link will be moved past its dead center position a small amount. It is obvious that as the toggle formed by the cylinder and link moves toward its dead center position, the associated ends of the levers 6 and l are moved apart, but that the force available for moving the lovers apart is only a component of the total force exerted by the piston, whereas, as soon as the toggle reaches its dead center position, the full force exerted by the piston i then available for moving the levers apart. The parts are further so proportioned that when the toggle formed by the link 20 and cylinder l2 has been moved to its dead center position, the braking bars will then be moved to the positions in which they are engaging the opposite side faces of a car wheel traversing rail I, and it follows, therefore, that while the full force of the piston is not available for moving the braking bars from their open position to the positions where the braking bars engage the car wheels, the force which is available under these conditions is more than adequate since the only force which has to be overcome is that due to the bias of the levers and friction. It also follows that when the braking bars are engaging the car Wheels, the full force exerted by the piston is then available to produce retardation of the car. In actual practice, the portion of the stroke of the piston required to move the braking bars to the positions where they just engage the car wheels is usually referred to as the clearance stroke, while the remainder of the stroke of the piston is usually referred to as the working stroke. For convenience, I shall hereinafter refer to these portions of the stroke of the piston in this manner.

When the lovers 6 and l have been moved apart by admitting fluid pressure to the motor M in the manner just described, and the cylinder I2 is subsequently disconnected from the source of pressure and connected to atmosphere, the free ends of the levers 6 and I will move toward each other under the influence of gravity. During this movement the toggle formed by the cylinder and link will remain in the position in which the basses 21a on the link engages the stop lugs 28a on the lever 9 until the piston is moved upwardly far enough to cause the cam surfaces 26a to engage the rollers l9a, whereupon continued movement of the levers will cause the link 20 to rotate in a clockwise direction about the pin 22 past the dead center position of the toggle formed by the lever and the motor M. As soon as the link has been rotated past the dead center position of the toggle, the toggle is, of course, broken, and as the free ends of the levers 6 and I complete their return movement, the

parts gradually return to their normal positions in which they are shown in Fig. 1.

One advantage of the means just described for moving the levers apart is that it enables the braking bars to be moved to their non-braking positions in which they are spaced from the rails far enough to clear wide locomotive wheels to their braking positions in which they engage the wheels of a car and retard the speed of a car, with a considerably shorter piston stroke than would otherwise be possible, thus decreasing the amount of fluid required to operate the retarder. According to actual tests, this decrease in fluid consumption amounts to from forty to fifty per cent of that which would be required to produce equivalent operation of the braking bars by means of a fluid pressure motor, the cylinder of which was connected directly to the one lever and the piston of which was connected directly to the other lever.

The supply of fluid pressure to the cylinder |2 of motor M is controlled by means of a fluid pressure operated exhaust valve 30 and a fluid pressure operated inlet valve 3|, which valves, in turn, are controlled by means of two pilot valves VI and V2.

The pilot valves VI and V2 are similar, and each comprises a valve stem 50 biased to an upper position by means of a spring 5|, and provided with a winding 52 and an armature 53. When valve VI is energized, as shown in the drawing, valve stem 50 of this valve moves downwardly against the bias exerted by the associated spring 5|, and under these conditions, a pipe 51 is connected with a pipe 54 which is constantly supplied with fluid pressure, usually air, from any suitable source not shown in the drawing. When valve Vi is deenergized, however, pipe 51 is disconnected from pipe 54 and is connected with atmosphere through a port 59.

When valve V2 is energized, valve stem 50 of this valve moves downwardly and connects a pipe 56 with a pipe 55, but when valve V2 is deenergized, as shown in the drawing, pipe 56 is disconnected from pipe 55 and is connected with atmosphere through a port 58.

The pipe 55 is constantly connected with the pipe 54 through a choke C, and is also connected with a reservoir RI. It will be apparent, therefore, that when the pipe 56 becomes connected with the pipe 54 in response to the energization of the valve V2, it will also become connected with the reservoir RI and with the source of fluid pressure, but that, the rate at which fluid is supplied to the pipe 56 from the source under these conditions will depend upon the setting of the choke C, and the volume of the reservoir RI. The function of the choke C and the reservoir RI will be made clear presently.

The valves 30 and 3| are both of the poppet type, and are both located in the same valve body 32. lower end of a valve stem 33, and is biased to an upper or closed position by means of a spring 34. The valve stem 33 extends upwardly through a guide 32a formed in a partition wall 32b which separates a chamber 320 from a cylinder 32d, and is attached at its upper end to a piston 38 reciprocably mounted in the cylinder 32d. The upper end of the cylinder 32d is connected with the previously described pipe 51, and it will be apparent, therefore, that when valve V2 is deenergized so that the pipe 51 is connected with atmosphere, spring 34 will hold valve 3| closed The exhaust valve 30 is secured to the and piston 38 in its upper position, but that, when valve V2 is energized, so that pipe 51 is connected with pipe 54, the fluid pressure which is then supplied to pipe 51 will force piston 38 to its lower position thus opening valve 3|. When valve 30 is opened, cylinder |2 of motor M becomes connected with atmosphere through pipe 31, a chamber 32e formed in valve body 32, valve 30, chamber 320, and a pipe 60, but when this valve is closed, cylinder |2 is disconnected from atmosphere.

Th inlet valve 3| is secured to the lower end of a valve stem 39, the upper end of which is secured to a shifting piston 40 disposed in a cylinder 32f formed in the valve body 32. The cylinder 32f is closed at its upper end by a cylinder head cap 32g provided with a cavity 32h which is connected to the pipe 56, and which serves as a reservoir R2 for a purpose which will be made clear presently.

Associated with the valve 3| are a primary spring 4| which biases the valv to a closed position, and a secondary spring 42. The spring 42 is maintained under an initial tension by means of a sleeve 43 and an adjusting screw 44. The adjusting screw 44 is arranged to be locked in its adjusted position by means of a nut 45, and is so adjusted that the valve 3| will be out of engagement with the sleeve when the valve is closed, but that, as soon as the valve has opened a small amount, usually about one-eighth inch in actual practice, the valve will move into engagement with the sleeve, whereupon both springs 4| and 42 will become elfective to yieldabl resist movement of the valve to its fully open position. The springs 4| and 42 are so proportioned that the valve 3| will open to the position in which it engages the sleeve 43 when the cylinder 32f is supplied with fluid at a relatively low pressure, but that a relatively high pressure is required to provide full stroke opening of the valve.

When the valve 3| is open, the pipe 54 is connected with the cylinder |2 through pipe 31, and it will be apparent, therefore, that under these conditions the motor M will be supplied with fluid pressure to move the braking bars to their brakingpositions. The rate at which fluid is supplied to the motor will depend, of course, upon whether the valve is opened to its initial position or to its full stroke position, and the parts are so proportioned that when the valve is opened to its initial position, the rate at which fluid is supplied to the motor will be reduced to an amount which is sufficient to prevent excessive shock while the retarder is closing.

The opening of the valve 3| is, of course, effected by energizing the valve VI to admit fluid to the cylinder 32f through the pipe 56. When the valve V2 becomes energized, it is desirable that the fluid supplied to the cylinder 32} through the pipe 56 should build up quickly to the relatively low pressure necessary to produce initial opening of the valve 3|, and then somewhat more slowly to the pressure at which the valve opens to its full extent, so that the valve 3| will throttle the air supply to the motor M until the retarder has closed, and will then immediately open to allow the pressure in th motor to build up rapidly to the desired working pressure. The reservoir R|, which, as was pointed out hereinbefore is connected between the valve V2 and the choke C, provides a means for causing the pressure in the cylinder 32) to build up quickly when the valve V2 becomes energized, while the time for the air pressure in the cylinder 32] to build up to the relatively high pressure necessary to cause the full opening of the valve is regulated by means of the choke C and by the volume of the reservoir R2 formed in the cap 329.

It will be seen from the foregoing that I have provided what amounts to a double action inlet valve for a fluid pressure operated car retarder, together with suitable means for controlling this valve, whereby the retarder can be caused to move to its closed position at a rate which is sufliciently slow to prevent excessive shock, and can then be immediately supplied with fluid at any desired working pressure to cause the re tarder to effect any desired degree of retardation.

Tests have shown that the time required to close the retarder and build up the pressure in the fluid pressure motor M to the full working pressure with the arrangement described is approximately four seconds, while a time of seven and one-half seconds would be required to produce the same results if a simple orifice were used in the air supply line to obtain a similar closing action.

The control of the valves VI and V2 forms no part of my present invention, and these valves may, for example, be controlled by the apparatus described and claimed in Letters Patent of the United States No. 2,023,635, granted to Delbert F. Cobourn on December 10, 1935, for Railway braking apparatus.

Although I have herein shown and described only one form of railway braking apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departin from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination, a car retarder, a fluid pressure motor for operating said car retarder, an inlet valve for controlling the admission of fluid to said motor, and means for controlling said inlet valve in a manner to cause it to initially open a small amount to close the retarder and to subsequently open a greater amount.

2. In a fluid pressure operated car retarder of the type in which the braking bars have a wide opening in their released positions and are moved to their closed positions by means of a fluid pressure operated motor and a link which together form a toggle that is moved from its collapsed to its dead center position when fluid is supplied to the motor, the combination of means for initially supplying fluid to said motor at a rate which is sufliciently slow to prevent shock when the toggle moves to its dead center position and for thereafter supplying fluid to said motor at a more rapid rate.

3. The combination with a fluid pressure operated car retarder of the type in which the braking bars are moved to their braking positions by a fluid pressure motor and a link which together form a toggle which is collapsed when the braking bars occupy their released positions but which moves to its dead center position when fluid is supplied to the motor, the combination of means for supplying fluid to said motor at a relatively slow rate to move said toggle from its collapsed to its dead center position and for thereafter supplying fluid to said motor at a difierent rate.

4. In combination, a fluid pressure operated car retarder, an inlet valve, means controlled by said valve for at times supplying fluid pressure ill Iii]

to said retarder, and means for controlling said valve in a manner to initially open it to a first extent and to thereafter open it to a greater extent.

5. In combination, a fluid pressure operated car retarder, an inlet valve, means controlled by said valve for at times supplying fluid pressure to said car retarder, and fluid pressure operated means for openin said valve in two stages to initially supply fluid pressure to said retarder at a rela tively slow rate and to thereafter supply fluid pressure to said retarder at a more rapid rate.

6. In combination, a car retarder, a fluid pressure motor for closing said retarder, a fluid pressure operated valve biased to a closed position by a spring which will permit said valve to open when fluid at a relatively low pressure is supplied to said valve, a second spring arranged to engage said valve when said valve has opened a relatively small amount and effective to prevent said valve from opening to its full extent except when said valve is supplied with fluid at a relatively high pressure, means for supplying fluid to said valve at a controlled rate, and means controlled by said valve for supplying fluid pressure to said motor.

7. In combination, a car retarder, a toggle operated by a fluid pressure motor for closing said retarder, an inlet valve for controlling the admission of fluid to said motor, and means for opening said valve to a first extent to cause said toggle to move to its dead center position and to thereafter open said valve to a greater extent to permit the fluid in the motor to build up quickly a to its working value.

8. In combination, a car retarder, a fluid pressure motor and a link which together form a toggle for closing said retarder, a fluid pressure operated valve biased to a closed position by a spring which permits said valve to become unseated when fluid at a relatively low pressure is supplied to said valve, a second spring effective to prevent said valve from opening more than a relatively small amount when said valve is supplied with fluid at said relatively low pressure and to permit said valve to open to a greater extent when said valve is supplied with fluid at a predetermined higher pressure, means including a choke for supplying fluid pressure to said valve from a source of fluid pressure, a reservoir associated with said valve for controlling the time required for the fluid pressure supplied to said valve to build up from said relatively low pressure to said predetermined higher pressure, a second reservoir arranged to initially supply said valve with fluid pressure at a rapid rate to the extent necessary to cause said valve to open said relatively small amount, and means controlled by said valve for supplying fluid pressure to said motor.

9. In combination, a fluid pressure Operated car retarder, a fluid pressure operated valve biased to a closed position by a spring which permits said valve to become unseated when fluid at a relatively low pressure is supplied to said valve, a second spring effective to prevent said valve from opening more than a relatively small amount when said valve is supplied with fluid at said relatively low pressure and to permit said valve to Open to a greater extent when said valve is supplied with fluid at a predetermined higher pressure, means including a choke for supplying fluid pressure to said valve from a source of fluid pressure, a reservoir associated with said valve for controlling the time required for the fluid pressure supplied to said valve to build up from said relatively low pressure to said predetermined higher pressure, a second reservoir arranged to initially supply said valve with fluid pressure at a rapid rate to the extent necessary to cause said valve to open said relatively small amount, and means controlled by said valve for supplying fluid pressure to said car retarder.

10. In combination, a fluid pressure operated valve biased to a closed position by a first spring which permits said valve to become unseated when fluid at a relatively low pressure is supplied to said valve, a second spring effective to prevent said valve from opening more than a relatively small amount except when said valve is supplied with fluid at a relatively high pressure, and means for supplying fluid pressure to said valve in a manner to initially open it said relatively small amount and to thereafter open to its full extent at the expiration of a predetermined time interval.

11. In combination, a fluid pressure operated valve biased to a closed position by a first spring which permits said valve to become unseated when fluid at a relatively low pressure is supplied to said valve, a second spring efiective to prevent said valve from opening more than a relatively small amount except when said valve is supplied with fluid at a relatively high pressure, and means including a choke and timing means for supplying fluid to said valve to cause it to quickly open said relatively small amount and to thereafter open to its full extent at the expiration of a predetermined interval of time.

12. In combination, a fluid pressure operated valve biased to a closed position by a first spring which permits said valve to become unseated when fluid at a relatively low pressure is supplied to said valve, a second spring efiective to prevent said valve from opening more than a relatively small amount except when said valve is supplied with fluid at a relatively high pressure, a source of fluid pressure, a pilot valve connected between said source and said first mentioned valve, a choke disposed between said source and said pilot valve, a first reservoir associated with said first mentioned valve to regulate the time required for the pressure to build up from said relatively low to said relatively high pressure, and a second reservoir disposed between said choke and said pilot valve and effective to supply sufficient fluid to said first mentioned valve to cause it to quickly open to said relatively small amount when said pilot valve is operated.

HERBERT L. BONE. 

